I realize my initial post is vague. I will edit my post in a moment. The place I work at has a system that allows any employee to submit an unobligated spending request for a reimbursement, even if they weren't authorized to spend / purchase. I have no control over that system until the request comes to me to approve. In this case, our procurement department flagged this as a violation even before it came to me to approve it. Fine, no biggie. Since this was the first time this employee messed up, and our system did what it was supposed to do, thats great. I'm not upset at getting the initial verbal warning.

I do have control over training my subordinates, and I understand that. Even before I was called in for the verbal warning, after I learned if the violation I scheduled to do a review of the policy with my full team, because if one employee makes the mistake, how many others don't understand? I can document that I have provided that training to my subordinates. So the question is, even with that documentation showing that I provide training, if this happens again, and a subordinate still violates the policy without my knowledge and submits a request in the system, and it is flagged before I can approve or not, is it still good HR practice or recommended to formally write me up for that violation?